This invention relates generally to a baler for forming cylindrical bales of crop material, commonly referred to as a round baler. More particularly, this invention pertains to a round bale wrapping apparatus having a simplified wrap material dispensing mechanism. Balers of this type generally have a bale forming chamber defined by an apron comprising an array of side-by-side belts, transverse slats mounted on chains, a plurality of rolls or a combination of these various elements, e.g., rolls and belts. Crop material, such as hay, is picked up from the ground as the baler traverses the field, and it is fed into a flexed or adjustable chamber where it is rolled up to form a compact cylindrical bale. The formed bale is wrapped in its compacted form by plastic film, net, twine or the like while still inside the bale forming chamber, and it is then ejected from the chamber onto the ground for subsequent handling.
Examples of prior art round balers of the general type mentioned above are the balers disclosed in U.S. Pat. No. 4,956,968 and U.S. Pat. No. 5,230,193 issued in the name of K. R. Underhill on Sep. 18, 1990 and Jul. 27, 1993, respectively. These balers include a mechanism for dispensing a net wrapping material into a bale forming chamber to circumferentially wrap a formed cylindrical bale. In both of these patents unique wrap material clamping arrangements are provided for inserting the loose end, the tail, of the wrap material into the chamber when the wrapping operation begins. In wrapping systems of this type it is crucial to good bale formation for the material to be wrapped snugly around the crop material and also to be evenly spread across the full width of the bale for substantially the full width.
However, the prior art wrap insertion and cutting mechanisms have been very complicated and were constructed using multiple (as many as ten) complicated rod linkages forming pivoted and sliding levers to insert the wrap material into a location from which it is carried around the bale. The need to cut the wrap material and the requirement to withdraw the wrap material insertion mechanism before starting a new bale required additional complicated lever actions. It would be very beneficial to have a less complicated wrapping mechanism both for the construction economy of requiring fewer parts to make and assemble the mechanism, and for the simplified maintenance requirements.
The present invention provides a simpler wrap feeding mechanism capable of feeding either net or film wrap, that uses the same shearbar knife as the prior art, wraps any size bale, and also allows less trash leakage than prior art wrap material feed systems.
The wrap material feeding mechanism of the invention is used with a conventional prior art round baler that has a main frame, a tailgate pivotally connected to the main frame and a sledge assembly mounted on the main frame for movement between a bale starting position and a full bale position. The sledge. assembly includes a plurality of rollers extending transversely across the main frame. The baler further includes an apron movably supported along a continuous path on the main frame and; on the tailgate with an inner course that cooperates with the rollers of the sledge assembly to define a bale forming chamber. The wrap material feeding mechanism of the invention is attached to the sledge assembly for dispensing sheet material into the bale forming chamber in a manner whereby the sheet material is wrapped around the curved sides of a cylindrical bale of crop material while the bale is in the bale forming chamber.
In the present invention, the knife and the wrap material feed mechanism, referred to as a xe2x80x9cduckbillxe2x80x9d because of its resemblance to the beak of a duck, are mounted on a floating cam arm that is linked to and moves with and in a plane parallel to the sledge arm that supports and moves the sledge rollers. Since the sledge arm moves with the sledge rollers as the bale grows, the floating cam arm, the duckbill, and the wrap material knife also move with the sledge rollers. This places the duckbill and the knife in the appropriate position relative to the bale, whether it is a full or partial bale, to begin the wrapping procedure at any time. All that is necessary is a single motion to insert the wrap material feeding mechanism, the duckbill, between two of the sledge rollers. From that location the tail of the wrap material, the cut section extending from the duckbill, is picked up by pinching it between the rotating lower sledge roller and the bulging bale, and the wrapping of the bale begins.
When the wrapping is completed, the motion of the duckbill is reversed and it is withdrawn from between the sledge rollers. This reverse motion is linked to and is accompanied by a simple motion of the wrap material cutting knife that moves the knife into contact with and cuts the wrap material. Since before the cut, the wrap material is held tautly between the wrapped bale and the retreating duckbill, the knife, which hits the wrap material approximately midway between the duckbill and the bale, easily cuts the material and leaves sufficient tail to begin the wrapping process when the duckbill is again inserted between the sledge rollers.
The simple motions that are required to first insert the duckbill between the sledge rollers and move the knife away from the wrap material, and then to withdraw the duckbill from the sledge rollers and move the knife to the wrap material and cut the material is accomplished by a single piston mounted on the floating cam arm. This piston produces a single motion by extending to insert the duckbill between the sledge rollers, and the piston withdraws to remove the duckbill from between the sledge rollers. The motion of the knife is accomplished by a single linking arm between the duckbill arm and the knife arm.
The present invention thereby accomplishes all the actions required to initiate and terminate the wrapping and to properly cut the wrapping material, and it does so with only four linked parts and an actuating piston, along with the prior art duckbill and shearbar knife.